The present disclosure relates to an electrophotographic image forming apparatus being capable of forming a single color monochrome image and a color image having a plurality of colors.
An image forming apparatus, such as a color printer, includes, for example, a plurality of photosensitive drums on which toner images of respective colors of black, yellow, magenta, and cyan are formed, and an intermediate transfer belt to which the toner images that have been formed on these plurality of photosensitive drums are transferred. With the plurality of photosensitive drums, a series of electrophotographic processes of electrification, exposure, development, and transfer are performed. The toner images of the respective colors that have been formed on the respective photosensitive drums are primary-transferred to the intermediate transfer belt, and then collectively secondary-transferred to a paper from the intermediate transfer belt. Thereby, a color image is formed on the paper.
The respective photosensitive drums are provided with a static eliminator (an eraser), which eliminates static electricity from the surface of the respective photosensitive drums by light irradiation. The static electricity elimination is performed after the transfer as a pre-treatment for electrification at the next time. Such static electricity elimination must be suppressed to a necessary minimum, because it involves light irradiation on the surface of the photosensitive drum, resulting in an optical fatigue thereof. Then, upon a monochrome image of a single color being formed, the static eliminators for the photosensitive drums of respective colors of yellow, magenta, and cyan that are used for forming a color image are controlled so as not to be lighted.